fix(#1262): adoption follow-ups - enumeration exclusion, SEND-honoring verdict suite, retire rc=2-is-normal guide text

- F5 (rev-code-02 blocker): sign test-send-message-glyph-agnostic.sh into
  test-enumeration-exclusions.txt beside its tmux siblings; the CI image
  ships no tmux, so the suite stays manually run (#1017 burndown).
- Adoption finding: the verdict suite hard-coded SEND to its sibling and
  ignored the SEND env var, so a red-first run against the shipping blob
  silently measured the patched copy instead (measured: shipping run
  printed PASS=4; with SEND honored it is PASS=3 FAIL=1, fixture 2 red,
  matching the recorded review numbers). SEND is now honored with the
  sibling as default, same contract as the glyph suite.
- F6/D19: framework FLEET-COMMS.md claimed 'rc=2 is the normal result
  when the target is an idle pi seat'. Post-fix rc=0 is normal for idle
  and busy pi seats; rc=2 on a healthy seat is a real report. Never-retry
  advice kept, softened to 'may be in the pane' for the unconfirmed arm.

Live verification on sb-it-1-dt (tmux 3.7b, pi glm-5.3 low, scratch
session): idle pi - shipping rc=2 'may be UNDELIVERED' while the seat
consumed the message and answered; patched rc=0 delivered, answered.
Busy pi mid-turn - shipping rc=2 while the pane accepted both messages
as steering input ('Steering: ...', 'Alt+Up to edit all queued
messages'); patched rc=0 delivered, both consumed and acted on after the
turn. Both D11 signatures: verdict now matches reality.

packages/mosaic/framework/guides/FLEET-COMMS.md

@@ -53,21 +53,23 @@ sends, it does not auto-reply.
 
 ### Exit codes
 
-| rc  | Meaning                                        |
-| --- | ---------------------------------------------- |
-| 0   | delivered or queued                            |
-| 1   | target session not found                       |
-| 2   | text reached the pane but is **still a draft** |
-| 3   | usage error (bad class, missing `-s`)          |
+| rc  | Meaning                                                                                      |
+| --- | -------------------------------------------------------------------------------------------- |
+| 0   | delivered or queued                                                                          |
+| 1   | target session not found                                                                     |
+| 2   | submission unconfirmed: draft still on the input line, or no positive evidence of submission |
+| 3   | usage error (bad class, missing `-s`)                                                        |
 
-**Never retry on rc=2.** The message is in the target pane; retrying double-sends it. Confirm
-instead:
+**Never retry on rc=2.** The message may be in the target pane, and a retry can double-send it.
+Confirm instead:
 
 ```bash
 tmux capture-pane -p -t <session>:0.0 | tail -20
 ```
 
-rc=2 is the normal result when the target is an idle pi seat.
+rc=0 is the normal result for both idle and busy pi seats (submission confirmed by draft
+transition, not by prompt glyph). rc=2 on a healthy seat is exceptional — treat it as a real
+report and investigate the pane.
 
 ## Durable comms